Side plate with reduced warp for heat exchanger and heat exchanger using the same

ABSTRACT

A warp of a side plate in the lengthwise direction is reduced by means of a simple shape formed by pressing without increasing a press machine in size. A side plate, for a heat exchanger, to be arranged at the end of a core section  13  composed of tubes  11  and fins  12  has a long and narrow shape with a U-shaped section formed by a bottom section  21  and bent sections  22  and  23  formed by bending both ends of the bottom section  21  in the width direction, and a plurality of recesses  24  extending in the width direction are formed by pressing the bottom section  21  at predetermined intervals c.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a side plate, for a heat exchanger,formed by bending so as to have a U-shaped section and a heat exchangerusing the same, and is preferably applicable to, for example, acondenser for vehicle air conditioning.

2. Description of the Related Art

In a conventional condenser for vehicle air conditioning, a side plateformed by bending so as to have a U-shaped section is arranged at theend of a core section composed of flat tubes and corrugated fins.Specifically, the side plate is joined by brazing to the corrugated finat the outermost side of the core section and to the end of a headertank and serves to reinforce the core section and protect the corrugatedfin, etc.

The side plate described above is, as shown in FIG. 5, a long and narrowmember having a U-shaped section formed by a bottom section 21 and bentsections 22 and 23 on both sides thereof, and its length dimension Lranges between approximately 250 mm and 850 mm in accordance with thespecifications of the condenser.

Being such a long and narrow member, a phenomenon occurs that the sideplate warps arch-wise in the lengthwise direction when the side plate isformed by bending a plate-like aluminum material using a press die so asto have a U-shaped section. This is because a residual stress state ofthe material is unbalanced. The reference letter “a” in FIG. 5 indicatesthe arch-like warp.

The cause of the occurrence of the warp a in the lengthwise direction ofthe side plate can be explained using FIG. 6. When forming the bentsections 22 and 23 by bending, a contracted (compressive) region A isformed in the inner part of the bent section and a stretched (tensile)region B is formed in the outer part of the bent section.

As the contracted (compressive) region A in the inner part of the bentsection and the stretched (tensile) region B in the outer part in thebent section exist concurrently, if the distortion of the side plate inthe lengthwise direction is observed, a stretched distortion C occurs inthe inner part of the bent section and a contracted distortion D occursin the outer part of the bent section. As a result, the side plate isbrought into an unbalanced stress state, under stress, because of thecoexistence of the contraction and stretch. Therefore, a phenomenonoccurs that the side plate warps arch-wise in the lengthwise direction.

The inventors of the present invention have also confirmed that thearch-like warp a reaches 5.6 mm when the length L=814 mm.

If such a large warp a occurs, it becomes difficult to assemble the endsof the side plate in the lengthwise direction to the ends of the headertanks in the core assembling process before integrally brazing acondenser. Further when integrally brazing a condenser, a gap isproduced between the side plate and the corrugated fin owing to the warpa, and poor joinability of the corrugated fin results.

Therefore, the inventors of the present invention have examinedcountermeasures such as so-called “forming in a holding state” in whichpressure is applied to the bent sections 22 and 23 of the side plate inthe direction of its height h, a countermeasure in which the backpressure to be applied to the bottom section 21 of the side plate isincreased, etc. However, as pressure must be applied to an area to bepressed of a wide range across the entire length of the side plate inthe lengthwise direction in any of these countermeasures, a highpressure is required and a large press machine is required. Because ofthis, the facility cost is raised and, therefore, these countermeasuresare not practical.

SUMMARY OF THE INVENTION

The above-mentioned points being taken into account, the object of thepresent invention is to reduce a warp of a side plate in the lengthwisedirection with a simple pressed form without the need to increase apress machine in size.

In order to attain the above-mentioned object, a side plate for a heatexchanger according to a first aspect of the present invention ischaracterized by being arranged at the end of a core section (13)composed of tubes (11) and fins (12), and having a long and narrow shapewith a U-shaped section comprising a bottom section (21) and bentsections (22, 23) formed by bending both ends of the bottom section inthe width direction thereof, and in that a plurality of recesses (24)extending in the width direction are formed by pressing the bottomsection (21) at predetermined intervals (c).

According to this aspect, by forming the plurality of recesses (24) onthe side plate bottom section (21) by pressing, a contracted region canbe formed not only in the inner part of the bent section of the sideplate but also in the outer part of the bent section.

Due to this, it is possible to bring the side plate into a balancedstress state, under no stress, and, as a result, the warp of the sideplate in the lengthwise direction can be reduced.

Further, the recesses (24) can be formed only by partly pressing thebottom section (21) at the predetermined intervals (c), and as it is notnecessary to apply a high pressure to the entire bottom section (21),the press machine can be prevented from becoming large in size.

In a side plate for a heat exchanger in a second aspect of the presentinvention according to the first aspect, the recesses (24) can be formedon the inner surface of the bottom section (21).

In a side plate for a heat exchanger in a third aspect of the presentinvention according to the first aspect, the recesses (24) may be formedon the outer surface of the bottom section (21).

In a side plate for a heat exchanger in a fourth aspect of the presentinvention according to any one of the first to third aspects, if therecesses (24) are formed into a shape having an arc-like section, therecesses (24) can be formed smoothly and the pressure to be applied forforming the recesses (24) can be reduced.

In a side plate for a heat exchanger in a fifth aspect of the presentinvention according to any one of the first to fourth aspects, therecesses (24) can be formed at the same time that the bent sections (22,23) are formed by bending.

In a side plate for a heat exchanger in a sixth aspect of the presentinvention according to any one of the first to fourth aspects, therecesses (24) may be formed after the bent sections (22, 23) are formedby bending.

A heat exchanger in a seventh aspect of the present invention ischaracterized by comprising a core section (13) including of tubes (11)and fins (12) and side plates (19, 20) arranged on the ends of the coresection (13), and in that the heat exchanger comprises the side plates(19, 20) for a heat exchanger in any one of the first to sixth aspects.

Due to this, it is possible to provide a heat exchanger capable ofexhibiting the function and effect in the first to seventh aspectsdescribed above.

A heat exchanger in an eighth aspect of the present invention accordingto the seventh aspect is characterized in that header tanks (14, 15)with which the ends of the tubes (11) are communicated respectively arearranged on both ends of the tubes (11) in the lengthwise direction, thefins (12) are corrugated fins (12), and the tubes (11), the corrugatedfins (12), and the header tanks (14, 15) are integrally joined bybrazing and at the same time, the side plates (19, 20) are integrallyjoined by brazing to the corrugate fins (12) located on the ends of thecore section (13) and to the ends of the header tanks (14, 15).

According to this aspect, in the heat exchanger assembled by brazing,the distance between the side plates (19, 20) and the corrugated fins(12) is reduced by reducing the warp of the side plates (19, 20) andthereby the joinability can be ensured and, at the same time, theworkability in assembling the side plates (19, 20) to the ends of theheader tanks (14, 15) can be improved.

The symbols in the parenthesis attached to each means described aboveindicate a correspondence with a specific means in the embodiments to bedescribed later.

The present invention may be more fully understood from the descriptionof the preferred embodiments of the invention set forth below, togetherwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a perspective view showing a general configuration of acondenser to which the present invention is applied.

FIG. 2A is partly broken perspective view showing a side plate accordingto a first embodiment of the present invention.

FIG. 2B is an essential part sectional view of the side plate in thelengthwise direction.

FIG. 2C is an essential part sectional view of the side plate in thewidth direction.

FIG. 3 is a diagram for explaining a function of reducing the warp ofthe side plate according to the first embodiment.

FIG. 4 is a partly broken perspective view showing a side plateaccording to a second embodiment of the present invention.

FIG. 5 is a perspective view showing a side plate according to the priorart.

FIG. 6 is a diagram for explaining the cause of the occurrence of thewarp of the side plate according to the prior art.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

The present embodiment relates to a condenser for vehicle airconditioning and, first of all, an outline of the condenser for vehicleair conditioning is explained by referring to FIG. 1. As is widelyknown, a condenser 10 is connected to the discharge side of arefrigerant of a compressor in a refrigerating cycle and cools andcondenses the gas refrigerant discharged from the compressor with theoutside air.

The condenser 10 has a core section 13 comprising a plurality of flattubes 11 extending in the horizontal direction and a plurality ofcorrugated fins 12, and on both the right end and the left end of thecore section 13, header tanks 14 and 15 having a substantiallycylindrical shape and extending in the vertical direction are arranged,and both ends of the flat tubes 11 are communicated with the inside ofthe header tanks 14 and 15.

At the upper part of the header tank 14 on one side, an inlet join 16through which a discharged gas refrigerant, from a compressor, flows in,is connected and at the lower part of the header tank 15 on the otherside, an outlet join 17 through which a refrigerant condensed and cooledin the core section 13 flows out, is connected.

The condenser 10 in the present embodiment forms a condensation section13 a for condensing a gas refrigerant at the upper part of the coresection 13 and a cooling section 13 b for cooling a liquid refrigerantafter condensation at the lower part of the core section 13. Then, areceiver 18 is integrally formed with the header tank 14 on the oneside, the refrigerant at the outlet of the condensation section 13 a isintroduced into the inside of the receiver 18, the refrigerant isseparated into gas and liquid in the receiver 18, and only the liquidrefrigerant is caused to flow into the cooling section 13 b.

On the other hand, side plates 19 and 20 are arranged on both the upperend and the lower end of the core section 13. The side plates 19 and 20have a long and narrow shape extending in the horizontal direction onboth the upper end and the lower end of the core section 13 and areformed by bending so as to have a U-shaped section.

Both ends of the side plate 19 in the lengthwise direction on the upperside are joined to the top ends of both the header tanks 14 and 15. TheU-shaped bottom section of the side plate 19 on the upper side comesinto contact with and is joined to the corrugated fin 12 at theuppermost part of the core section 13.

Both ends of the side plate 20 in the lengthwise direction on the lowerside are joined to the bottom ends of both the header tanks 14 and 15.The U-shaped bottom section of the side plate 20 on the lower side comesinto contact with and is joined to the corrugated fin 12 at thelowermost part of the core section 13. A plurality of mounting holes 19a and 20 a are bored in the side plates 19 and 20 and the condenser 10is mounted to the body of a vehicle using the mounting holes 19 a and 20a, and means such as screw fixing.

The constituent members 11, 12, and 14 to 20 of the condenser shown inFIG. 1 are formed of aluminum alloy and are assembled into a structureshown in FIG. 1, and the assembled body is brought into a heating ovenwhile being held with a jig. The assembled body is heated to atemperature higher than the melting point of the brazing material in theheating oven and each member is integrally brazed into a single unit.

Because of this, in order to smoothly carry out assembling of thecondenser before the brazing process and ensure excellent brazingproperties, it is important to keep the arch-like warp a (refer to FIG.6 described above) of the side plates 19 and 20 in the lengthwisedirection as small as possible.

Countermeasures to reduce the arch-like warp a in the present embodimentare explained based on FIGS. 2A and 2B. FIG. 2A is a partly brokenperspective view of the side plates 19 and 20, FIG. 2B is an essentialpart sectional view of the side plates 19 and 20 in the lengthwisedirection, and FIG. 2C is an essential part sectional view of the sideplates 19 and 20 in the width direction (direction perpendicular to thelengthwise direction).

The side plates 19 and 20 each have a U-shaped section formed by thebottom section 21 and the bent sections 22 and 23 located on both theright end and the left end of the bottom section 21 in the widthdirection. The material of the side plates 19 and 20 is a bare aluminummaterial with no clad brazing material. JIS (Japanese IndustrialStandard)-A 3003 is used in the present embodiment, and its thickness tis, for example, 1.6 mm.

A plurality of recesses 24 having a minuscule depth b of the bottomsection 21 are parallel formed on the U-shaped inner surface at constantintervals c across the entire length of the side plates 19 and 20 in thelengthwise direction. The recess 24 has a long and narrow shapeextending in the width direction of the bottom section 21 and itssection has an arc shape (R-shape) with a predetermined radius as shownin FIG. 2B. The depth is, for example, as minuscule as 0.04 mm. Thewidth d of the recess 24 is, for example, 1.5 mm.

The length f of the recess 24 is 8 mm. Here, the width dimension e ofthe bottom section 21 is, for example, 12.8 mm and, therefore, thelength f of the recess 24 occupies 60% or more of the width dimension eof the bottom section 21.

On each of both ends of the recess 24 in the lengthwise direction, aslope surface 24 a is formed so that both ends of the recess 24 in thelengthwise direction are smoothly connected to the inner surface of thebottom section 21. Here, the angle θ between the slope surface 24 a andthe line vertical to the bottom section 21 is, for example, 75°.

The formation of the above-mentioned recesses 24 can be carried outtogether with the formation of the side plates 19 and 20 by bending. Inother words, protrusions (rib-shaped) each having an arc-like sectionfor partly pressing the bottom section 21 at the constant intervals care formed in advance in a press die for forming by bending a plate-likealuminum material into a side plate comprising the bottom section 21 andthe bent sections 22 and 23 and having a U-shaped section. Due to this,it is possible to form the U-shaped section by bending using the pressdie and simultaneously to form a number of recesses 24 by pressing.

The reason why it is possible to reduce the warp of the side plates 19and 20 by forming the recesses 24 by pressing is explained below. Asshown in FIG. 3, it is possible to produce a contraction stress E byforming the recesses 24 by pressing and thereby, a contraction region Fis formed also in the outer part of the bent section.

In other words, the stretched (tensile) region B in the outer part ofthe bent section in FIG. 6 is changed to the contracted region F in thepresent embodiment, that is, both the regions in the inner part and inthe outer part of the bent section are the contracted (compressive)regions A and F and a balanced stress state, under no stress, isestablished.

As a result, it is possible to reduce the arch-like warp of the sideplate in the lengthwise direction by producing a stretched distortionboth in the inner part and in the outer part of the bent section in thelengthwise direction of the side plate and at the same time, bringingthe stretched distortions in the inner part and in the outer part of thebent section into a balanced state.

The inventors of the present invention measured the magnitude of thearch-like warp a while changing the interval c between the recesses 24based on the above-mentioned design example with the total length L=814mm, and obtained the following results.

Interval c=40 mm . . . warp a=2.6 mm

Interval c=30 mm . . . warp a=1.5 mm

Interval c=20 mm . . . warp a=0.3 mm

As described above, it has been found that the warp a=5.6 mm in theconventional example shown in FIG. 5 can be more than halved by settingthe interval c between the recesses 24 to a value equal to or less than40 mm.

From the results discussed above, it will be understood that the smallerthe interval c, the more the warp a can be reduced. However, if theinterval c is reduced excessively, the contracted region F in the outerpart of the bent section becomes dominant over the contracted region Ain the inner part of the bent section and the side plates. 19 and 20warp in the opposite direction of the warp a shown in FIG. 5. Therefore,in the present embodiment, it is preferable to set the lower limit ofthe interval c to around 20 mm.

According to a study by the inventors of the present invention, it ispossible to form the recesses 24 after forming the side plates 19 and 20by bending. It has been confirmed that the arch-like warp a can besimilarly reduced in this manner.

On the other hand, if the formation of the recesses 24 on a plate-likealuminum material is carried out before the formation of the side plates19 and 20 by bending, a phenomenon occurs in that, due to the residualstress accompanying the formation of the recesses 24, the plate-likealuminum material warps in the opposite direction of the warp a in FIG.5. The occurrence of the warp makes it difficult to insert theplate-like aluminum material into the press die. Therefore, it is notpreferable to carry out the formation of the recesses 24 before theformation of the side plates 19 and 20 by bending.

Second Embodiment

Although the recesses 24 are formed on the inner surface of the bottomsection 21 of the side plates 19 and 20 having a U shaped section in thefirst embodiment, the recesses 24 are formed on the outer surface of thebottom section 21 in the second embodiment as shown in FIG. 4.

It has been confirmed that even if the recesses 24 are formed on theouter surface of the bottom section 21 as described above, the warp acan be reduced as in the first embodiment.

However, as is seen from FIG. 1, the corrugated fin 12 is joined bybrazing to the outer surface of the bottom section 21 of the side plates19 and 20 and, therefore, the formation of the recesses 24 on the outersurface deteriorates the joinability (brazing properties) between theside plates 19 and 20 and the corrugated fin 12. Therefore, from theviewpoint of the joinability, the first embodiment is preferable to thesecond embodiment.

Other Embodiments

In the above mentioned embodiments, although the shape of the section ofthe recess 24 is an arc, it is also possible to obtain the same effectto reduce the arch like warp a even if the shape of the section of therecess 24 is formed into a trapezoidal shape. However, as a trapezoidalshape is formed of combined flat surfaces, the pressure to be appliedfor forming the recesses by pressing is increased compared to the caseof an arc shape.

In the above mentioned embodiments, although the interval c between therecesses 24 is constant across the entire area of the bottom section 21in the lengthwise direction, it may be possible to change the interval cbetween the recesses 24 in the lengthwise direction of the bottomsection 21 as the need arises.

In the above mentioned embodiments, examples are shown in which thepresent invention is applied to the side plates 19 and 20 in a condenserin a refrigerating cycle, however, the present invention can besimilarly applied to a heat exchanger such as a radiator because sideplates having a U shaped section are mounted on a heat exchanger such asa radiator for cooling the cooling water for a vehicle engine.

While the invention has been described by reference to specificembodiments chosen for the purposes of illustration, it should beapparent that numerous modifications could be made thereto, by thoseskilled in the art, without departing from the basic concept and scopeof the invention.

1. Side plates for a heat exchanger arranged at ends of a core sectioncomprising tubes and fins, wherein the side plates with a U shapedsection comprising a bottom section and bent sections formed by bendingboth ends of the bottom section in a width direction thereof, and aplurality of recesses extending in the width direction are formed bypressing the bottom section at predetermined intervals.
 2. The sideplates for a heat exchanger as set forth in claim 1, wherein therecesses are formed on an inner surface of the bottom section.
 3. Theside plates for a heat exchanger as set forth in claim 1, wherein therecesses are formed on an outer surface of the bottom section.
 4. Theside plates for a heat exchanger as set forth in claim 1, wherein eachof the recesses has an arc like section.
 5. The side plates for a heatexchanger as set forth in claim 1, wherein the recesses are formed atthe same time that the bent sections are formed by bending.
 6. The sideplates for a heat exchanger as set forth in claim 1, wherein therecesses are formed after the bent sections are formed by bending.
 7. Aheat exchanger comprising a core section including tubes and fins andside plates arranged at the ends of the core section, wherein the heatexchanger comprises the side plates for a heat exchanger as set forth inclaim
 1. 8. The heat exchanger as set forth in claim 7, wherein: headertanks with which ends of the tubes are respectively communicated arearranged on both ends of the tube in the lengthwise direction; the finsare corrugated fins; the tubes, the corrugated fins, and the headertanks are integrally joined by brazing; and each of the side plates isintegrally joined by brazing to the corrugated fin located on the end ofthe core section and to ends of the header tanks.